A disk in a disk drive for data storage may build up electrostatic charge on its surfaces. Such electrostatic charge can be generated by several mechanisms including rubbing with surrounding components in the disk drive (e.g., the disk cartridge or shuttle), human or robotic handling of the disk cartridge that causes transfer and accumulation of electrostatic charge to the disk, and tribological charging of the disk by contacting the read-write head.
In many optical disk drives, a disk embossed with grooves and pits for tracking and servo and a cartridge for holding the disk are usually made of non-conductive materials. For example, these materials such as plastic, dielectric materials, or other non-conductive materials can be prone to build-up of static charge and may be charged up to a high static voltage. In a near-field optical disk drive, where the optical head is spaced from the disk during operation by less than one wavelength (e.g., a small fraction of one wavelength), static charge on the disk surface can accumulate to a static voltage on the order of several kilo volts.